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1. Field of the Invention
The invention relates to telecommunications, and in particular, to systems that provide access to broadband systems from Integrated Services Digital Network (ISDN) systems or systems that can be converted into the ISDN format.
2. Background of the Prior Art
FIG. 1 depicts a common prior art arrangement for local telecommunications access. Shown are Customer Premises Equipment (CPE) that are connected to a local switch. Typically, there is more CPE connected to each local switch, but the number depicted has been restricted for purposes of clarity. A standard connection between CPE and the local switch is the well known Time Division Multiplexed (TDM) connection using the Extended Superframe (ESF) format. The TDM/ESF connection allows multiple devices at the customer site to access the local switch and obtain telecommunications services.
TDM employs time division multiplexing to combine multiple communications paths into a single digital signal. ESF employs robbed bit signaling. In robbed-bit signaling, particular bits of user information in the bearer channels are replaced by signaling information. Thus, these signaling bits are xe2x80x9crobbedxe2x80x9d from the user bearer channels. In ESF, the robbed bits are known as the ABCD bits. Since the ABCD bits are integrated into the bearer channels, ABCD robbed-bit signaling is an xe2x80x9cin-bandxe2x80x9d signaling system. Examples of information carried by the ABCD bits are off-hook and on-hook conditions. ESF and ABCD robbed-bit signaling are well known in the art.
The ISDN format is also well known. ISDN provides a user with a digital connection to the local switch that has more bandwidth and control than a conventional local loop. ISDN has bearer channels (B) and a signaling channel (D) that are typically combined at the primary rate (23B+D) or at the basic rate (2B+D). Because ISDN has a separate signaling channel (the D channel), it has an out-of-band signaling system.
At present, broadband systems are being developed and implemented. Broadband systems provide telecommunications service providers with many benefits, including higher capacities, more efficient use of bandwidth, and the ability to integrate voice, data, and video traffic. These broadband systems provide callers with increased capabilities at lower costs. However, CPE using the TDM, ISDN or similar formats cannot directly access these broadband systems. These systems need an interworking interface to the sophisticated broadband systems. Telecommunications service providers also need such an interface in order to use their broadband systems to provide services to CPE that use ISDN format or a format that can be converted into ISDN.
The invention includes a telecommunications system for use between an Asynchronous Transfer Mode (ATM) system and an ISDN system for telecommunications calls. The telecommunications system comprises a signaling processing system and an ATM multiplexer. The signaling processing system is operational to process call signaling from the ISDN system and from the ATM system. It selects at least one of an ISDN connection and an ATM connection for each call and provides control messages that identify the selected connections. The ATM multiplexer is operational to exchange the call signaling between the ISDN system and the signaling processing system. It also receives the control messages from the signaling processing system and interworks call communications between the ISDN system and the ATM system on the selected connections based on the control messages.
In some embodiments, the invention is also operational to interwork the ISDN signaling and Signaling System #7 (SS7) signaling. In some embodiments, the invention is also operational to interwork between communications and signaling from another system and ISDN bearer communications and ISDN signaling. In some embodiments, the invention is also operational to exchange Signaling System #7 (SS7) signaling with the ATM system. In some embodiments, the invention includes an ATM cross-connect, a signaling processor that is operational to process signaling to select connections, a signaling converter that is operational to interwork ISDN signaling and SS7 signaling, and/or an ISDN converter that is operational to interwork between communications and signaling from the other communications system and ISDN bearer communications and ISDN.
The invention could be a method for operating a telecommunications system that interworks between an ISDN system and an Asyncronous Transfer Mode (ATM) system for telecommunications calls. The method comprises receiving ISDN signaling and ISDN bearer communications into the telecommunications system and converting the ISDN signaling into Signaling System #7 (SS7) signaling. The method includes processing the SS7 signaling to select ATM connections, and interworking the ISDN bearer communications with the selected ATM connections. In some embodiments, the method includes receiving SS7 signaling and ATM communications into the telecommunications system, processing the SS7 signaling to select ISDN connections, and interworking the ATM communications with the selected ISDN connections.